Method of making dental broaches.



. W. W. FOWLER.

METHOD OF MAKING DENTAL BROACHES. APPLICATION FILED MAY 14. 1913.RENEWED APR- 9. I915.

LlfiUfiUfi. Patented NovI-16, 1915.

jm eizhr- COLUMBIA PLANDGRAPH (IO-,WASHXNUTON. D. c.

intrinsic snares Parana cr m WILLIAM w. rownnn, or wnsrnnctron, DISTRICTorcoLUMBIA.

. METHOD OF MAKING DENTAL BROACHES.

Licorice.

Specification of Letters Patent. Patented NQV. 1915.

Original application filed September 24, 191.2,Seria1 No. 722,023.Divided and this application filed lrtay 14, 1913, Serial No. 767,659.Renewedhpril 9, 1915. Serial No. 20,322.

To all whom it may concern:

Be it known that 1, WILLIAM W. Fownnn, a citizen of the United States,residing at l/Vashington. in the District of Columbia, have inventedcertain new and useful 1m? provements in Methods of Making DentalBreaches, of which the'followingis a specification. x

This invention relates to a novel method of making dental broaches ofthe type shown in my prior Patent No. 1.067.015, dated July 8, 1918,application No. 722,023, filed September 24., 1912 of which the presentapplication is a division, in which patented structure the prong portionof the broach is universally flexible and flat-twisted to produce abroach which is practically unbreakable and adapted to serve thecombined function of a nerve extractor and a canal reainer.

The object of the invention is to provide a method whereby breaches ofthis type may be easily. effectively and economically produced.

In the accompanving drawing illustrating the invention: Figure 1 is aplan view of'the blank from which the broach is made, showing the sameat the completion of the first step of manufacture. Fig. 2 is atransverse section on line 22' of Fig. 1. Fig. 3 is a plan view of theblank as it appears after the completion of the second step. Fig. 4: isa transverse section on the line 44 of Fig. 3. Fig. 5 is a plan view ofthe blank as it appears after the completion of the third step. Fig. 6is a transverse section on the line 66 of Fig. 5. Fig. 7 is a view ofthe completed broach. Fig. 8 is an enlarged detail section on the line88 of Fig. 7

In carrying my invention into practice I take a piece of roundspring-tempered wire of the desired length and gage and shape the buttend 1 in any suitable manner. after which the prong portion 2 isrendered of greater flexibility than the handle or shank portion 3 bytapering said prong portion longitudinall and uniformly toward itspointed extremity as shown. This is accomplished by grinding or fillingthe prong portion until it accurately fits within a grooved tem'plet orother gaging device whereby accuracy in shaping the prong is insured,the heat generated by the grinding or filing operation also givingadesirable finishing temper.-

The blank produced as above described, and shown in Fig. 1, is thenpolished and the entering end 4 finally pointed to the desired degree,after which the acting portion of. the prong 2 is flattened as shown at5 in Figs. 8 and 42.2 This acting portion may be made of anylongitudinal extent desired. as a. result of which the flexibility andtransverse dimension of said portion is increased in one direction andcurved surfaces 6 left at the longitudinal edges of the flattenedsection. These edges 6 are next ground down to substantially planesurfaces 77, forming at their angles of intersection with the remainingsides ,of the flattened section 5 longitudinal cutting or reaming edges8. as shown in Figs. 5 and 6. The blank thus'far prepared is then placedin a suitable chuck or holder and by any suitable means turned orrotated to twist the portion 5, as illustrated in Figs. 7 and 9. showingthe completed broach, forming a continuous double coil or spiral 9having continuous longitudinal reaming or cutting edges 10 and 11 and aterminal entering point'12. These cutting or reamingedges are preferablyplane'surfaced, in order to prevent the waste of material encountered informing barbs or spurs thereon, whereby the cost of manufacture isincreased on account of the number of defective broaches which must bediscarded as unfit for service but under some conditions the reamingedges may be barbed or spurred to meet trade re quirements.

The broach constructed as above described is provided with aspirally-coiled portion which is longitudinally tapered and pointed vand thus adapted to be readily inserted into a root canal, and which isalso provided with. cutting edges adapted to ream the wall of the canaland thuh remove all tissue during the rotation of the broach, wherebythe nerve will be positively engaged for extraction and the canal at thesame time thoroughly cleaned. The portion of the prong between thecoiled part 9 and the handle or shank is freely flexible, while theflattened twist of the coiled portion has a wide amplitude of universalfiexibilitv, thus allowing the broach to be bent to dispose the coiledportion at any required working angle without liability of fracture.

The described construction of the twist or coil 9 produces an extractingand reaming surface which has a screw-like action when the broach isrotated in a clockwise direction, thus adapting the vbro'achfor use inpenetrating and cleaning out very small canals without the objectionablepressure required in the use of broaches of ordinary construction; "Thisallows the broach to be fed forward until the end of a canal is reachedwithout liability of its becoming broken 01f within the canal or ofbeing forced through the canal and entering and infecting thetoothsocket.

By the use of a fiat-twist the coiled portion, if it should to causeinfection or decay.

in prpepee l preierpblp prerirle per p i i a suitable character forindicating the eX- tent-to which the broach may be inserted to reach,theend' ofthe' root canal of .anaverage tooth, thus enabling a dentistto determme to an approximately accurate degree 1 'ust how far thebroach has been" inserted so that he may workwith proper confidence andcaution to prevent undue projection of the broach when the indicatingmeans registers with the outer end of the canal or .some other suitableportion of the tooth in connection with which the indicating means isemployed as: a gage. To this end, the

upper surface of the broach may be blued or otherwise rendered ofcontracting color or appearance to the lower surface thereof, such asfrom the butt end 1 to a point 12 on the prong, the distance of whichfrom the entering point 12 will indicate the distance to which the prongmay be safely introduced within a root canal of an average length,

Having thus described my invention, I claim:

"1. The herein described method of making a dental broach, whichconsists in grinding'or filling a primarily circular springtempered-blank to form a tapered prong, flattening said tapered prong,reducing the rounded edges of the flattened and tapered prong to planesurfaces, and then twisting said tapered and flattened prong uponitself.

2. The herein described method of making a dental broach, which consistsin first tekinp' a circular piece of spring tempered a e I 0 i n r r e pr e pee, prpplrep er. .hhep tee ppe re re te taper from a; point betweenits ends to one of its extremities, flattening the reduced portion ofthe wire, grinding or filing the rounded edges of the flattened portionto smooth surfaces, pointing the extremity of said flattened portion,and then twisting said flattened portion upon itself.

In testimony whereof I afiix my signature in presence of two witnesses.

WVILLIAM V. FOWLER. Witnesses E. EnMoNs'roN, J12, C. C. HINES.

Copies of this patent may be obtained forfive cents each, by addressingthe Commissioner of Patents,

1 Washington, 13.0.

